In building construction, it is often advantageous to utilize the lightweight roof panels in the roof as a structural element or diaphragm in resisting lateral forces on the walls of the building. This is particularly important in buildings of the type having a non-rigid frame, and wherein metal roof panels are used, as for example in wide buildings or when load bearing concrete walls or the like are used, or for braced walls or post and beam structures. In wide buildings, there are of necessity several lengths of roof panels on the roof, and in order to properly handle thermal expansion and contraction, the roof panels, when made of metal, have cooperating structure such as slotted holes at one of their ends to allow for endwise slippage between adjacent panels and between the panels and a portion of the secondary framing of the building. Obviously, such structure in the prior art eliminates the effectiveness of the roof panel or panels in resisting lateral forces on the building.
Moreover, in wide building designs wherein load bearing walls or the like are used and where interior gutters and the like are used and the roof panels thus cannot be attached to the wall or other vertical load carrying member, the panels of the roof are not effective to resist lateral forces on the building.
The above problems are particularly acute when light gauge steel roof panels are connected to a secondary frame such as Z purlins which are, in turn, secured to roof beams, as is typical in most metal, pre-engineered buildings. Because of the simplicity, economy of design, and ruggedness and durability of metal, pre-engineered buildings utilizing light gauge steel roof panels secured to a secondary frame which is, in turn, secured to a primary frame in a building construction, some means in the roof structure of enabling the roof structure to resist lateral forces on the building is highly desirable.
The present invention provides a roof construction in which a secondary framework is attached to a primary frame of the building and a plurality of roof panels are attached to the secondary framework, and wherein brace means or shear connectors are connected between a predetermined number of the elements of the secondary framework such that the entire roof structure is rigidified and lateral forces are thus enabled to be transferred from the side walls of the building through the primary frame and secondary frame and into the panels of the roof structure, which effectively transfer these forces to the end shear walls or other rigid structure at the ends of the building.
More particularly, the present invention relates to a metal, pre-engineered building construction in which light guage steel roof panels are attached to a secondary frame comprising a plurality of Z purlins, which are attached to the roof beams of the primary frame of the building. With the roof construction of the present invention, interior gutters may be used without deteriorating the effectiveness of the roof panels in resisting lateral forces on the building, and wide building construction may be used wherein more than one panel is connected in end-to-end relationship, with slotted holes for thermal expansion and contraction provided therebetween. The invention is equally as effective when exterior gutters, or other arrangements, are utilized in the building construction.
Specifically, the present invention comprises a channel-shaped brace that is connected between two adjacent purlins of a roof structure, with one brace for each length of roof panel and with the brace positioned substantially centrally of an associated roof panel. The brace thus prevents rotation of the purlins about their longitudinal axis and thereby rigidifies the roof structure and eliminates the need for structural attachment of the roof panels to the wall members or elements of the building construction, except at the end wall of the building where gutters are not normally required. In effect, each roof panel acts as a diaphragm to resist lateral forces, and yet the provision for thermal expansion and contraction is not adversely affected. The roof is comprised of individual diaphragms that are as wide as each roof panel is long.
The present invention also allows the use of metal roof panel, Z purlin construction, with load bearing, precast or tilt up wall panels, and the invention allows the transfer of the load from the purlins into the panels without affecting provisions for expansion and contraction of the panels, and also eliminates the need for expensive bracing of the building construction, such as cross bracing rods and the like.